Google search for: "Idle no more" movement site:ca gets many hits, but on the first page there is a CBC news article about it from January 5, 2013. This article says: "In late October, four women in Saskatchewan began exchanging emails about Bill C-45, which had just been introduced in Ottawa. Jessica Gordon, Sheelah McLean, Sylvia McAdams and Nina Wilsonfeld were concerned the bill would erode indigenous rights."

If you are near a large public or academic library, it is well worth checking newspaper databases such as Proquest or LexisNexis Academic. Lexis is generally available only at academic libraries, but if you change its default search of Major World Publications to All News, the search: "idle no more" pre/5 movement gets 993 hits. When you change the sort to "oldest to newest", it shows 2 articles from December 10, 2012; several from December 11 and many more from mid December - very many from western Canada sources.

We will need to wait a bit for scholarly articles on it; Academic Search Premier gets only 11 hits for its default search of title, abstract, subject headings and journal titles for: "idle no more", and none are in "scholarly/ peer reviewed" journals. Even if you "select a field" TX All Text, it finds no hits for the phrase in academic journals.